Thermo Scientific HB-S2000, Руководство пользователя

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Sarasota 2000 Ultrasonic Multipath
Flowmeter
Section 2, SYSTEM COMPONENTS, Page 2-12 Thermo Fisher Scientific
SYSTEM COMPONENTS
2.3.3.2.3 16 bit BCD I/O and encoder input
The 16 bit parallel BCD signal may act as either input or output according to the jumper links
LK1 and 3 on the board. See Fig 6. The default condition is for BCD INPUT – no links, for
example from a shaft encoder counter.
The format is 5 Volt positive logic, though the input can accept inverted logic if specified via
the screens (Appendix 1: LCD Screens).
Handshaking is via strobes STRB1 and STRB2. STRB1 relates to bits 1 to 8 and STRB2 to
bits 9 to 16.
There are two 25 way female D connectors labelled BCD1 and BCD2. BCD1 is connected to
I/O option card 1 if fitted and BCD2 to I/O option card 2 if fitted.
BCD input
•
When used as an input, the 4 digit BCD number is normally used as an auxiliary level.
•
Operating units are selected via the screens (Appendix 1: LCD Screens) or GAFA
(Appendix 2: GAFA Screens).
•
The BCD number may have an offset applied – “level above datum” if BCD zero does not
correspond to the flowmeter zero level.
•
The BCD number may also have a scaling factor applied, for example if a BCD
incremental value of 10 corresponds to 5 mm, the scaling factor is 0.5.
•
If the scaling factor is given a negative sign, the BCD input will be taken as negative logic
(low is “1”)
•
For BCD input, the STRB is pulled low for 0.2 ms by the Sarasota 2000 when it wants
data.
BCD Output
•
When used as an output, the function of the 4 digit BCD number and operating units are
selected via the screens (Appendix 1) or GAFA (Appendix 2). Typically the function will
be flow or water level.
•
For BCD output, the STRB is pulled low for 0.2 ms whilst valid data is being presented.
•
BCD output may be uncoded, in which case the BCD number is taken as it appears, or
coded in which case the first digit indicates a range/sign and the remaining 3 digits the
value. The coding is defined as follows:
Coding for flow
The data is represented as a 4 digit number where the most significant digit is the code:
0 = multiply by 10
0
(i.e. x 1)
1 = multiply by 10
1
(i.e. x 10)
2 = multiply by 10
2
(i.e. x 100)
3 = fault condition, no data
4 = negative flow multiply by 10
0
(i.e. x -1)
5 = negative flow multiply by 10
1
(i.e. x -10)
6 = negative flow multiply by 10
2
(i.e. x -100)
The three remaining digits are the three most significant digits of the reading;
e.g.
Flow + 4.28 m3/s Output 0428
Flow +34.28 m3/s Output 1342
Flow - 0.15 m3/s Output 4015
Coding for level
The level data is presented as a 4-digit number, representing the last 4 digits of the displayed
value.
e.g.
Flow + 4.123 m Output 4123
Flow +52.678 m Output 2678